JERUSALEM — Israel and Hamas have agreed to a 72-hour humanitarian cease-fire beginning Friday, during which time there will be negotiations on a more durable truce in the 24-day-old Gaza war, the United States and United Nations announced Thursday.

The announcement comes hours after Israeli Prime Minister Benjamin Netanyahu vowed to destroy Hamas’ tunnel network with or without a cease-fire” as the Palestinian death toll soared past 1,400 — surpassing the number killed in Israel’s last major invasion of Gaza five years ago. There was noo immediate Israeli comment on the announcement.

In a statement released in New Delhi where Secretary of State John Kerry is traveling, the U.S. and U.N. said they had gotten assurances that all parties to the conflict had agreed to an unconditional cease-fire.

“This humanitarian cease-fire will commence at 8 a.m. local time on Friday, Aug. 1, 2014. It will last for a period of 72 hours unless extended. During this time the forces on the ground will remain in place,” the statement said.

“We urge all parties to act with restraint until this humanitarian cease-fire begins, and to fully abide by their commitments during the cease-fire.”

The statement said the cease-fire was critical to give civilians a much-needed reprieve from violence. During this period, civilians in Gaza will receive humanitarian relief and have time to bury the dead, take care of the injured and restock food supplies. The time also will be used to repair water and energy infrastructure.

There was no immediate Israeli comment on the cease-fire annoncement.

Earlier, the Israeli military said it was calling up an additional 16,000 reserve soldiers to pursue its campaign against the Islamic militants.

At least 1,441 Palestinians have been killed, three-quarters of them civilians, since hostilities began on July 8, according to Gaza health officials — surpassing the at least 1,410 Palestinians killed in 2009, according to Palestinian rights groups.

Israel says 56 soldiers, two Israeli civilians and a Thai agricultural worker have died — also far more than the 13 Israeli deaths in the previous campaign.

As the toll grew, U.N. High Commissioner for Human Rights Navi Pillay accused both Israel and Hamas militants of violating the rules of war.

She said Hamas is violating international humanitarian law by “locating rockets within schools and hospitals, or even launching these rockets from densely populated areas.” But she added that this did not absolve Israel from disregarding the same law.

The Israeli government, she said, has defied international law by attacking civilian areas of Gaza such as schools, hospitals, homes and U.N. facilities. “None of this appears to me to be accidental,” Pillay said. “They appear to be defying — deliberate defiance of — obligations that international law imposes on Israel.”

Pillay also took aim at the U.S., Israel’s main ally, for providing financial support for Israel’s “Iron Dome” anti-rocket defense system. “No such protection has been provided to Gazans against the shelling,” she said.

At the United Nations, Israel’s Ambassador Ron Prosor responded to criticism of his country, saying: “I think the international community should be very vocal in standing with Israel fighting terrorism today because if not, you will see it on your doorstep tomorrow.”

Israel expanded what started as an aerial campaign against Hamas and widened it into a ground offensive on July 17. Since then, Israel says the campaign has concentrated on destroying cross-border tunnels militants constructed to carry out attacks inside Israeli territory and ending rocket attacks on its cities.

Israel says most of the 32 tunnels it uncovered have now been demolished and that getting rid of the remainder will take no more than a few days.

“We have neutralized dozens of terror tunnels and we are committed to complete this mission, with or without a cease-fire,” Netanyahu said Thursday in televised remarks. “Therefore, I will not agree to any offer that does not allow the military to complete this important mission for the security of the people of Israel.”

For Israel, the tunnel network is a strategic threat. It says the tunnels are meant to facilitate mass attacks on civilians and soldiers inside Israel, as well as kidnappings, a tactic that Hamas has used in the past. Palestinian militants trying to sneak into Israel through the tunnels have been found with sedatives and handcuffs, an indication they were planning abductions, the military says.

Several soldiers have been killed in the current round of fighting by Palestinian gunmen who popped out of underground tunnels near Israeli communities along the Gaza border.

Israeli defense officials said the purpose of the latest call-up of 16,000 reserves was to provide relief for troops currently on the Gaza firing line, and amounted to a rotation that left the overall number of mobilized reservists at around 70,000. They spoke on condition of anonymity in line with regulations.

However, Israeli officials have also said they do not rule out broadening operations in the coming days.

Palestinians have fired more than 2,850 rockets at Israel — some reaching major cities but most intercepted by the Iron Dome defense system. On Thursday alone, more than 100 rockets were fired toward Israeli cities, the army said.

One Israeli was seriously wounded when a rocket exploded in a residential area of Kiryat Gat in southern Israel, the military said. The rocket damaged a house and destroyed several cars parked on the street. Another rocket was intercepted over Tel Aviv by Israel’s rocket defense system, the army said.

Gazans said munitions struck the Omar Ibn al-Khatab mosque next to a U.N. school in the northern town of Beit Lahiya. The office of the military spokesman said Palestinian snipers inside the mosque had shot at troops, wounding one Israeli soldier and prompting retaliatory fire.

The strike in Beit Lahiya damaged water tanks on the roof of a building near the mosque, sending shrapnel flying into the adjacent school compound, where dozens of Palestinians displaced by the fighting had taken shelter.

“The shrapnel from the strike on the mosque hit people who were in the street and at the entrance of the school,” said Sami Salebi, an area resident.

Gaza health official Ashraf al-Kidra said at least 15 people were wounded in the strike, including three who were in critical condition.

Among them was Kifah Rafati, who was being treated for shrapnel injuries at the nearby Kamal Adwan Hospital. She said she and her six children had been sleeping in a classroom inside the U.N. school when the explosion went off.

“There is no safety anywhere,” the 40-year-old Rafati said.

Hamas has said it will only halt fire once it receives guarantees that a Gaza border blockade by Israel and Egypt — tightened after the Islamic militant group violently seized power in Gaza in 2007 — will be lifted.

Israel says it wants to decimate Hamas’ rocket-launching capability, diminish its weapons arsenal and demolish the tunnels. It has launched more than 4,000 strikes against Hamas-linked targets, including rocket launchers and mosques where it says weapons were being stored.

Israeli strikes have also hit dozens of homes. Mahmoud Abu Rahma of the Palestinian human rights group Al Mezan said nearly half of the Palestinians killed so far died in their homes.

More than a quarter of a million Palestinians in Gaza— over 236,000—are seeking shelter in 86 UNRWA installations, according to UNRWA spokesman Chris Gunness.

Israel says it is trying hard to avoid civilian casualties and blames Hamas for using civilians as “human shields.” Israel has issued warnings before attacks through phone calls and text messages to residents among other methods.